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Re: gEDA-user: Free Dog meetings at MIT starting this September!
On Aug 22, 2004, at 2:23 PM, Karel Kulhavý wrote:
Ok, you really made me laugh with this one, which is a big surprise
with the mood I'm in today. :-)
I am using transformer gun with that loop of thick wire at the end.
I must strongly disagree with this statement. The notion that
neophyte to solder.
through-hole soldering is easier than soldering surface-mount devices
is, and always has been, a myth. Personally, any more, I *hate*
soldering through-hole parts. Sure it takes a steadier hand due to
finer pin spacings and such, but give me an SOIC over a DIP any day.
Perhaps a part of the problem is that people want to be able to
solder with a cheap soldering iron they bought at Radio Shack for $12
Isn't it possible to get away with the sioldering without a soldering
That'd be "wave soldering". Wave soldering is useful for
through-hole parts, but for SMT assembly, "reflow soldering" (see
below) is the way to go.
at all? The manufacturing lines are using allegedly some kind of solder
flowing in circles that makes a bulge on the surface of the liquid and
the PCB is stuck into the bulge. At least someone has been describing
me this way.
Isn't it possible to heat up amount of solder in an old pot or pan,
Sure. But "reflow soldering" is much more practical. I'm gearing up
for that here right now. You take "solder paste" (a mix of finely
powdered solder and flux) and apply it to SMT pads with a syringe. You
stick the components ("pick and place") onto the board, they adhere to
the solder paste. This is done either manually or automatically. Then
you "bake" it in an oven with a very carefully controlled
temerature/time profile until it melts, and surface tension
automatically [mostly] centers the components on the pads. Solder
masks on the PCBs keep inter-pin shorts to a minimum. The results are
usually very clean, very consistent, and very, very reliable.
handful of rosin and then carefully dip the board into it?
Large multi-zone conveyor ovens are used for this in assembly houses,
but they cost a fortune and require an immense amount of electricity to
run. Lately some companies have started making small benchtop reflow
ovens (that's what I'm getting) which are practical for prototyping and
low-volume production. There are reports of hobbyists having success
with VERY CAREFUL use of a household toaster oven (don't use the one
you use for food...buy a separate one, as nasty chemicals [lead solder,
flux] are involved!) but I would not try this for a "professional"
application. True purpose-built reflow ovens have very accurate
control of their temperature, are designed for very even and very fast
heating, and have blowers for fast cool-down.
I have once seen in TV how some guy was casting tin soldiers this way
Yup, a lot of people do that. It's pretty easy to do.
Someone has also described a homebuilt thru-plating station (however it
isn't still probably a finished design yet).
Now this is something I'd like to see. :-) URL?
Just add a homemade 150 000 rpm compressor-driven spindle PCB drill
linear X-Y drives and 2um precision and you can save walking to PCB
manufacturer (however the machine weighs 6 tons - I fear it would
probably fall through the room's floor ;-) )
Well...there are limits. ;)
Dave McGuire "...it's a matter of how tightly
Cape Coral, FL you pull the zip-tie." -Nadine Miller